This invention relates generally to multicomponent mats and their method of manufacture. In particular, the invention relates to a method of making a multi-component mat of glass fibers and natural fibers using a natural fiber slurry and a glass fiber slurry and the mats formed by this method.
U.S. Pat. Nos. 5,965,638 and 6,146,705 disclose structural mat matrices comprising a substrate consisting essentially from 80% to 99% by weight fiberglass fibers, from 20% to 1% by weight wood pulp and from 5% to 15% by weight binder.
A method for making a bicomponent mat of glass fibers and pulp fibers is disclosed in my copending application, U.S. Ser. No. 09/474,449, the disclosure of which is incorporated herein by reference. The mat is formed from pulp and glass fibers. The pulp fibers have a length of from about 0.05 inch to about 0.2 inch.
It would be desirable to form mats having natural fibers with lengths that exceed the lengths of pulp fibers so as to enhance the strength characteristics of the final mat.
Generally, the multicomponent mat of the present invention is formed from glass fibers and natural fibers. The process involves forming a natural fiber slurry comprising natural fibers having a length between about 0.2 inch (5 mm) and about 2.0 inches (51 mm) and water. The natural fiber slurry may include a cationic polymer. The next step involves dispersing glass fibers in, for example, a white water. The natural fiber slurry and the glass fiber slurry are compatible with one another and are combined to form a multicomponent furnish or slurry.
The mats of the present invention have several advantages. First, they contain natural fibers which can be easily burned during a disposal process once the useful life of a final product in which a mat is incorporated has ended or can be easily recycled. Second, the mats have high strength characteristics, especially high tear strength. The mats of the present invention may be incorporated into such products as shingles and automotive headliners.
The method of this invention involves making a multicomponent mat of glass fibers and natural fibers comprising the steps of: forming a natural fiber slurry by mixing natural fibers and water, a cationic polymer may or may not be added; forming a slurry of glass fibers by mixing together a dispersant, water, glass fibers, and a viscosity modifier; combining and mixing the natural fiber slurry and the slurry of glass fibers to form a wet mat; and removing any excess moisture. A binder may also be applied to the wet mat. If applied, the binder may be cured during the moisture removal step.